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Definition: extinction from Philip's Encyclopedia

Dying out of a species or population. Extinction is part of the process of evolution in which certain species of plants and animals die out, often to be replaced by others.


extinction

From The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide
In biology, the complete disappearance of a species from the planet. Extinctions occur when a species becomes unfit for survival in its natural habitat usually to be replaced by another, better-suited species. An organism becomes ill-suited for survival because its environment is changed or because its relationship to other organisms is altered. For example, a predator's fitness for survival depends upon the availability of its prey. Past extinctions Mass extinctions are episodes during which large numbers of species have become extinct virtually simultaneously in the distant past, the best known being that of the dinosaurs, other large reptiles, and various marine invertebrates about 65 million years ago between the end of the Cretaceous period and the beginning of the Tertiary period, the latter known as the K–T extinction . There have been several others in the more distant past. There is disagreement about the causes, but one of several major catastrophes have been blamed, …
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Full text Article extinction

From Astronomy Encyclopedia
Loss of light from the line of sight as it passes through a medium. The loss may be by SCATTERING , in which case the light energy is taken up by the medium and promptly re-emitted at the same energy but redirected out of the line of sight. Or the loss may be by ABSORPTION , in which case the light…
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Full text Article extinction

From The Columbia Encyclopedia
in biology, disappearance of species of living organisms. Extinction usually occurs as a result of changed conditions to which the species is not suited. If no member of the affected species survives and reproduces, the entire line dies out, leaving no descendants. This was the case with the…
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Full text Article Extinction

From Edinburgh Companions to Literature and the Humanities: The Edinburgh Companion to Animal Studies
We live in an era of extinction. Blockbuster films and nightly news stories fixate on threats to human existence, whether viral contagion or alien annihilation. Scientists warn of humanity's destructive impacts, endangering other species and the fragile ecologies on which all depend. Orangutans in…
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Full text Article extinction

From Encyclopedia of Evolution
Extinction is the disappearance of a species. Extinction usually involves (1) a decrease in population sizes within a species and (2) a decrease in genetic diversity within a species. These two processes are related, since small populations usually have less genetic diversity than large populations. …
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Full text Article Extinction

From Encyclopedia of Special Education: A Reference for the Education of Children, Adolescents, and Adults with Disabilities and Other Exceptional Individuals
Extinction, also termed planned ignoring, is a behavior-reductive procedure that occurs when a behavior that has been previously reinforced is no longer reinforced in order to reduce or eliminate the occurrence of that behavior ( Sulzer-Azaroff & Mayer ,). Extinction has been used to effectively…
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From The Penguin Dictionary of Science
The termination of the existence of a species or population. Extinction is an inevitable function of the evolutionary process in which new species arise and replace previously existing ones. Whilst species extinction is an inexorable process, there have been five ‘mass extinction’ events in the…
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From Keywords for Environmental Studies
Most life forms that have ever existed—over 99 percent, according to some scientists—are extinct. Extinction is, therefore, one of the most basic characteristics of the planet's ecology. Species disappear because they change through gradual adaptation to such a degree that they can no longer be…
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Full text Article Extinction

From 50 Biology Ideas You Really Need to Know
Extinction
While our planet's current collection of organisms might seem impressive, it is but a fraction of the biodiversity over time: over 99 per cent of species have disappeared during the history of life on Earth. Most went extinct slowly, but some species have died out relatively rapidly, due to mass…
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Full text Article extinction

From The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide
In biology, the complete disappearance of a species from the planet. Extinctions occur when a species becomes unfit for survival in its natural habitat usually to be replaced by another, better-suited species. An organism becomes ill-suited for survival because its environment is changed or because…
| 531 words
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Full text Article extinction

From The Macquarie Dictionary
the act of extinguishing. Plural: extinctions the fact of being extinguished; condition of being extinct. Plural: extinctions suppression; abolition; annihilation. Plural: extinctions Biology a becoming extinct; a coming to an end or dying out. Plural: extinctions The permanent disappearance of…
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